The present invention relates to a passenger detecting apparatus which determines the presence of a passenger or an object, such as a child seat, on a seat apparatus, accurately estimates the weight of a passenger, or determines or classifies the build or the seating posture of a passenger seated on a seat.
Passenger restraint systems, such as an air bag system, a seat-belt pretensioner and a force limiter are often equipped around, for example, the seat apparatus of an automobile to secure the safety of a passenger. If those passenger restraining systems are used inadequately or wrong, however, the passenger restraint systems may hurt a passenger. If an air bag is activated while a woman of small build is driving with her face close to the steering wheel, the abrupt inflation of the air bag may cause a face injury. If an air bag is activated with a child sitting in the front of a front passenger seat, the inflation of the air bag likewise may injure the child.
To prevent harmful effects from being done by the restraint systems that should guarantee safety of a passenger, it is desirable to adequately activate the passenger restraint systems around the seat apparatus in accordance with the build of a passenger seated on a seat.
In a case of an air bag system, for example, there is a demand of attaching a passenger detecting apparatus to a seat unit to determine the build of a passenger and performing such control as to inflate the air bag normally when the passenger is determined as an adult of a standard size, to slow the air-bag bag inflation time when the passenger is determined as an adult of small build and not to inflate the air bag and secure safety only with a seat belt when the passenger is determined as a child.
Accordingly, consideration is given to what is called a smart air bag system which controls an air bag in accordance with the build of a passenger. There are various systems of using the position or the like of a passenger on a seat besides build information such as the weight and height, as threshold values for the build of a passenger. Of those systems, the most promising one is the system that controls an air bag according to the build information of a passenger. Specifically, this system determines the weight of a passenger to make classification and controls the air-bag inflation time, air-bag inflation strength or the like.
One example of a passenger detecting system which makes such decisions as to if a passenger is in a danger zone and whether the passenger is a child or an adult is introduced in U.S. Pat. Nos. 5,573,269 and 5,670,853.
The passenger detecting systems described in those publications have weight sensors located around a seat, i.e., under the seat, under the seat fabric and under the floor mat under feet, a back-rest angle sensor located in the back rest and a height sensor located above a passenger and detect the weight and position of the passenger by a combination of those sensors.
Those systems combine at least four sensors, which lead to a higher cost.
In the case where a load sensor is provided under a seat, to accurately detect the weight of a passenger, it is necessary to consider the load applied under the feet of the passenger in addition to the load detected by this load sensor. If a weight sensor is located under the floor mat as described in the aforementioned publications to acquire the load applied under the feet, the positions of the feet of a passenger differ depending on the build and posture of the passenger. This makes it difficult to accurately detect the load applied under the feet.
That is, to measure the value of the load on a seat and control the air-bag inflation time and air-bag inflation strength in accordance with the weight of a passenger, the accurate weight information of the passenger should be acquired. Even with a combination of a plurality of sensors, instruments or the like, it is difficult to make accurate measurements due to the posture of a passenger, a change in ambient temperature, a change in humidity, vibration of a vehicle and so forth. In this respect, in consideration of a variation of each measured value, it seems adequate to classify the weight of a passenger into classes having certain ranges.
It is also necessary to consider a case where an infant or a child is seated in a child seat (an auxiliary seat for a child including an infant seat and a booster seat). Specifically, the height to the head of an infant or a child, the distance to the dash board, the restraint force to the seat and so forth greatly differ from those in the case where a female adult of small build is seated. It is therefore demanded not to activate the supplemental systems around a seat, such as an air bag, unnecessarily. Since the value of the load applied to a seat in the case where a child is seated using a child seat is close to the load value in the case where a female adult of small build is seated, however, accurate passenger information may not be obtained so that the supplemental systems around a seat, such as an air bag, may be activated unnecessarily. Therefore, it is also necessary to adequately classify the weight of a passenger and to securely detect, particularly, the case where an infant or a child is seated on the car seat via a child seat.
There has been an antenna/tag system which has a tag provided on a child seat side and determines whether or not a child seat is in use by emitting radio waves toward the tag from a seat unit to detect the presence of the tag. While it is possible to determine whether or not a child seat is in use using this system, such a tag should not necessarily be provided on a child seat and when a child seat without such a tag is attached to the seat unit, the passenger detecting apparatus may erroneously determine that an adult is seated on the seat unit, resulting in an unnecessary activation of restraint systems, such as an air bag.
Japanese Unexamined Patent Publication (KOKAI) No. Hei 9-150662 discloses the structure that has a distortion gauge provided between a seat cushion and a plurality of brackets for securing the seat cushion to the floor of a vehicle. This structure merely makes reliable detection of the presence or absence of a seated person without being influenced by the seating position of the seated person on a seat, but cannot adequately classify the weight of a passenger on a seat and surely detect, particularly, the case where an infant or a child is seated on the seat via a child seat.
When the load that is applied to the seating surface using a passenger detecting apparatus, just changing the angle of the back rest, for example, significantly changes the load applied to the seating surface even if the same person is seated. This makes it difficult to estimate the size of the passenger""s weight. Specifically, for example, the load that is applied to the seating surface in the case where a woman of small build is seated with the back rest set fully upright is close to the load in the case where a man of a standard size is seated with the back rest tilted slightly, so that the build cannot be determined accurately.
If such a type of passenger detecting apparatus is used in, for example, controlling an air bag, it is not possible to perform inflation of an air bag according to the build of a passenger seated on a seat or necessary inflation of a front-seat-passenger""s air bag.
The aforementioned passenger detecting apparatus needs a sensor for detecting weight information to determine the build of a passenger. As this sensor, a load sensor for detecting the weight of a passenger has been proposed. Load sensors 410a to 410d are provided between a seat cushion pan 411 and springs 412 or a seat mounting section 413 to detect the weight of a passenger, as shown in FIG. 51.
As the aforementioned load sensor, an electric capacitance type or a distortion gauge or the like is used. The electric capacitance type load sensor detects the weight from a change in the electric capacitance caused by a load-induced change in the distance between electrodes, and the load sensor that uses the distortion gauge detects the weight from a load-induced change in resistance.
While those load sensors are excellent in acquiring an output proportional to the amount of a change in weight (a change in electric capacitance, resistance), the acquired output is the amount of a change in weight and the accurate weight of a seated passenger cannot be detected unless the initial value of the load sensor is set accurately.
The initial value corresponding to the initial weight of the load sensor is likely to drift due to the influence of a change in the ambient environment, such as the temperature, so that accurate weight detection is difficult.
The load applied to the load sensor is the sum of the weight of a passenger and the weight of a seat. However, the weight of a seat varies depending on the type of a vehicle, and further depending on the attaching position of the load sensor. It was therefore necessary to correct the initial value according to such a difference. As the initial value of the load sensor differs depending on the mechanical attaching state of the sensor, it should be corrected for each sensor and a manual work or the like is troublesome and takes time.
It is an object of the present invention to provide a passenger detecting apparatus which determines the presence of a passenger or an object on a seat unit and determines the build of a passenger to improve the availability of seat""s peripheral units, such as passenger restraint systems.
It is another object of this invention to provide a passenger detecting apparatus which adequately classifies the weight of a passenger on a seat and reliably detects, particularly, the case where an infant or a child is seated on the seat via a child seat.
It is a further object of this invention to provide a passenger detecting apparatus which accurately estimates the weight of a passenger on a seat.
It is a still further object of this invention to provide a passenger detecting method and system which easily corrects the initial value of weight detection means to be able to improve the precision in detecting the weight of a passenger.
To achieve the above objects, a passenger detecting apparatus according to this invention is characterized by comprising first detection means for detecting presence of a passenger or an object on a seat cushion; and decision means for determining whether the passenger is sitting on the seat cushion or the object is present thereon based on the first detection means.
As it is possible to accurately determine the state of an object lying on the seat cushion of a seat unit, the passenger detecting apparatus, when used in a seat unit of an automobile, can determine whether a child seat or a cargo is on the seat unit or a passenger of a relatively small build is sitting, so that restraint systems for passenger safety, such as an air bag, and other peripheral systems of the seat can be activated properly.
When the passenger detecting apparatus is used in a passenger seat unit in a vehicle, an airplane or the like, it is possible to remotely detect the passenger occupying state of the seat unit.
It is preferable that in the passenger detecting apparatus, the first detection means has at least a dielectric sensor and a pressure sensor.
Because it is determined if a passenger or an object is present on a seat cushion based on the detection result of the pressure sensor and determine whether it is a passenger or an object by means of the dielectric sensor, it is possible to reliably distinguish a passenger from an object as well as the presence or absence of a passenger or an object on the seat cushion.
It is preferable that in the passenger detecting apparatus, the first detection means has at least a dielectric sensor and a temperature sensor.
It is possible to determine that a passenger is seated only when the temperature sensor and the dielectric sensor both satisfy certain conditions and determine that an object is lying on the seat cushion when one of the temperature sensor and the dielectric sensor satisfies certain conditions.
It is preferable that in the passenger detecting, the decision means also determines whether or not there is moisture sticking on the seat cushion based on detection results of the dielectric sensor and the pressure sensor or detection results of the dielectric sensor and the temperature sensor.
In the case where decision is made based on the detection results of the dielectric sensor and the pressure sensor, it is possible to detect that moisture is sticking on the seat cushion when the presence of a passenger or an object is not detected from the detection result of the pressure sensor and the dielectric sensor satisfies certain conditions.
It is preferable that the passenger detecting apparatus comprises second detection means for detecting presence and a seating state of a passenger in a seat cushion; third detection means for detecting a contact state of the passenger to a back rest; angle detection means for detecting an angle defined by the seat cushion and the back rest; and decision means for determining presence/absence and a build of the passenger based on the second detection means, the third detection means and the angle detection means.
As the build of a passenger is determined not only from the seating state of the passenger on the seat cushion but also from the state of contact of the passenger to the back rest and the angle defined by the seat cushion and the back rest, the build of a passenger can be determined accurately regardless of the tilt angle of the back rest.
Therefore, when the passenger detecting apparatus is used in the seat unit of an automobile, for example, restraint systems for passenger safety, such as an air bag, and other peripheral systems of the seat can be activated properly.
When the passenger detecting apparatus is used in a passenger seat unit in a vehicle, an airplane or the like, it is possible to roughly and remotely detect the ratio of an adult, a child or the like occupying the seat unit, ensuring the use in in-vehicle (in-flight) services or the like.
It is preferable that in the passenger detecting apparatus, the second detection means has at least one of a dielectric sensor, a pressure sensor and a temperature sensor.
It is possible to precisely acquire the position of the buttocks of a passenger on a seat cushion from the end position of the output in the case of the dielectric sensor or the temperature sensor and from the peak position of the output in the case of the pressure sensor, and use it in determining the build of the passenger.
It is preferable that in the passenger detecting apparatus, the third detection means has at least one of a dielectric sensor, a pressure sensor and a temperature sensor.
A sensor of a different type from the sensor that is used as the second detection means can be used for the third detection means, and the shoulder position of a passenger at the back rest can be accurately obtained from the end position of the detection output of the sensor and can be used in determining the build of the passenger.
It is preferable that in the passenger detecting apparatus, the second detection means uses at least one of the first detection means as recited in claim 1.
By using at least one of the first detection means is used as the second detection means, it is possible to determine the presence of a passenger or an object on a seat unit, distinguish them from each other and determine the build of the passenger with fewer detection means.
It is preferable that in the passenger detecting apparatus, the pressure sensor comprises a plurality of independent pressure sensor elements arranged in the seat cushion in a matrix form, and the decision means determines whether a passenger is sitting on the seat cushion or an object is present thereon and also determines a build of the passenger if sitting on the seat cushion, based on detection results of the dielectric sensor and the pressure sensor element.
Because it is distinguished and determined whether a passenger is sitting on the seat cushion or an object is lying thereon by the combination of the pressure sensor and the dielectric sensor located in the seat cushion and the pressure sensor elements are arranged in a matrix form in the seat cushion, it is possible to accurately determine the build of a passenger only on the seat cushion side.
A passenger detecting apparatus according to this invention is characterized by comprising first detection means for detecting a distribution of a load applied to a seat cushion of a vehicle; second detection means for detecting a seat weight of a vehicle and a load applied to an entire seat; and decision means for classifying a passenger sitting on the seat based on the detection results of the first detection means and the second detection means.
From the distribution of the load applied to the seat cushion of a vehicle acquired by the first detection means, it is possible to detect if a person is seating on the seat or a child seat or an object is lying thereon, and allow the second detection means to detect the load applied the entire seat including the weight of the seat and adequately classify the weight of a passenger on the seat, and detect the case where an infant or a child is seated on the seat via a child seat.
A passenger detecting apparatus according to this invention is characterized in that decision means classifies a passenger sitting on the seat based on the detection results of first detection means for detecting if there is a child seat on a seat in a vehicle and second detection means for detecting a seat weight of a vehicle and a load applied to an entire seat.
As the first detection means detects the presence or absence of a child seat and the second detection means detects the load applied the entire seat including the weight of the seat, it is possible to adequately classify the weight of a passenger on the seat, and detect reliably, particularly, the case where an infant or a child is seated on the seat via a child seat.
A passenger detecting apparatus according to this invention is characterized by comprising load measuring means for measuring a weight of a seat on which a passenger sits and a weight of the passenger applied to the seat; barycenter position detection means for detecting a barycenter of the passenger on the seat; and weight estimation means for estimating the weight of the passenger by correcting a measured value of the load measuring means based on information from the barycenter position detection means.
Without arranging extra weight sensors around a seat, the load measuring means can measure the weight of a seat on which a passenger is seated and the weight of the passenger on the seat, and this measured value can be corrected based on information from the barycenter position detection means so that the weight of the passenger can be estimated accurately.
A passenger detecting apparatus according to this invention is characterized by comprising load measuring means for measuring a weight of a seat on which a passenger sits and a weight of the passenger applied to the seat; barycenter position detection means for detecting a barycenter of the passenger on the seat; and seating posture estimation means for estimating a seating posture of the passenger based on information from the barycenter position detection means.
It is possible to accurately estimate the seating posture of a passenger without arranging extra weight sensors around a seat.
It is preferable that in the passenger detecting apparatus, the barycenter detection means uses the load measuring means located at at least two or more different positions of the seat.
The use of the load measuring means located for the barycenter detection means eliminates the need for specially providing a sensor as the barycenter detection means, thereby reducing the number of sensors.
It is preferable that in the passenger detecting apparatus, the barycenter detection means comprises a pressure-sensitive film having a plurality of pressure-sensitive sensor elements arranged in the seat.
As the barycenter of a passenger on a seat can be detected accurately by a plurality of pressure-sensitive sensor elements provided in the pressure-sensitive film, the weight of the passenger can be estimated accurately.
It is preferable that in the passenger detecting, apparatus, the seat is movable on seat rails and the barycenter detection means also detects a barycenter of the passenger with respect to the seat rails.
As the barycenter detection means detects the barycenter of a passenger with respect to seat rails as well as the barycenter of the passenger on the seat, the front seating of the passenger can be detected reliably.
It is preferable that in the passenger detecting apparatus, the barycenter detection means has detection means for detecting a position of a head of the passenger.
By detecting the position of the passenger""s head, it is possible to detect the load applied to the feet of a passenger more accurately and estimate the weight of the passenger more accurately.
It is preferable that in the passenger detecting apparatus, the barycenter detection means has detection means for detecting a width of buttocks of the passenger.
As the width of the buttocks of a passenger is statistically proportional to the weight, it is possible to reliably estimate the weight in a special case such as the weight of a child whose feet do not reach or an adult who is sitting with the feet lifted up by computing the estimated weight of the passenger from the width of the buttocks of the seated passenger, comparing it with the value of the weight that is corrected and computed by the barycenter detection means and using a lighter one.
A passenger detecting apparatus according to this invention detects a weight of a passenger who sits on a seat in a vehicle by weight detection means and acquiring secondary information about the passenger based on the detected weight information, and comprises passenger detection means for detecting if there is a passenger on the seat; acquisition means for acquiring the weight information detected by the weight detection means when the passenger detection means detects no passenger; and correction means for correcting an initial value of the weight detection means based on the weight information.
As the initial values of the individual load sensors that constitute the weight detection means are corrected based on weight information from each load sensor when the passenger detecting apparatus which constitutes the passenger detection means detects the absence of a passenger on a seat in a vehicle, the correction of the initial values of the load sensors can be carried out easily.
When there are a plurality of weight detection means, the difference between the weight detections by the individual weight detection means caused by a difference in the type of a vehicle or a difference in the attaching state can be suppressed uniformly by correcting the initial values of the corresponding weight detection means based on the weight information from the individual weight detection means.